Siren



May 24, 1949. I FLETCHER 2,471,028

SIREN Filed 'Dec. 5, 1945 5 Sheets-Sheet 1 j 22 I B 66 ail? Jmmydmmer May 24, 1949. J. F. FLETCHER SIREN 3 Sheets-Sheet 2 Filed Dec. 5, 1945 portion A of the siren includes a rear portion a, directly attached to the base or standard B, and a front end cap or cover b. These two housing parts are detachably connected by the screws (5.

The front end of the housing part a is provided with an annular series of ports or openings 8 through which air under pressure is discharged to produce the siren sound. These ports or open ings are clearly shown in Figs. 1 and 5. In this particular form of siren, there are eight such discharge ports. It is to be understood, however, that a greater or lesser number of discharge ports can be employed Without in any way affecting the invention.

The housing part a of the siren body has suitably mounted therein an electric motor, not shown. Figs. 3, 6 and 7 illustrate a bearing structure 9 that is employed for supporting the power output end ID of the armature shaft of the motor.

Figs. 3, 5, 6 and 7 disclose the hub portion ll of an impeller mounted on the end N of the armature shaft and held thereon by the set screws I2. The impeller further includes a series of eight radial blades l3 which are formed with circumferentially extending vanes M at their outer edges. These vanes are of proper dimensions circumferentially toleave openings I between their free edges and the portions of the next adjacent impeller blades l3. These openings i5 are arranged in alignment with and correspond in size and shape with the discharge ports 8 that are formed in the housing part a of the siren body. It will beappreciated that during each complete revolution of the impeller, the eight vanes l4 will alternately register with, and thereby close, the discharge ports 8 formed in the housing part a and will alternately register radially with the portions of the housing part a that are located between the discharge ports 8. Consequently, each one of the ports 8 will be closed eight times and opened eight times during each complete revolution of the rotor. This alternate opening and closing of the discharge ports 8 functions to produce the siren sound as air under pressure is expelled or discharged through the opened ports.

To bring about circulation of the air under pressure, the inner side of the impeller is completely closed by a 'wall [8 while the outer side of the impeller is partially closed by the annular wall N. This annular wall is left open at its center to admit air to the impeller blades [3.

Figs. 3, 4 and 5 disclose a control sleeve l8 that is interposed between the periphery of the impeller and the portion of the siren housing part a that is provided with the air discharge ports 8. This control sleeve I8 is formed with openings l9 that are circumferentially spaced the same distance as and are shaped the same as the ports 8 of the housing part a and the openings l5 formed in the periphery of the impeller. Therefore, when the openings IQ of the control sleeve register with the discharge ports 8 of the siren housing part a, the air under pressure developed by the impeller blades will be discharged through the ports 8. This condition of alignment is illustrated in Fig. 5. It will be understood, however, that if the control sleeve [8 is moved angularly a proper distance, the solid portions of the control sleeve will close the discharge ports 8 of the siren housing part a. When these discharge ports 8 are closed, the air placed in circulation under pressure by the impeller will not be permitted to discharge through the ports 8 and no sound will be produced. It is intended, therethe desired results.

4 fore, that the control sleeve be actuated so that it will be oscillated back and forth into and out of position for alternately closing and opening the discharge ports 8 to bring about intermittent interruption in the production of the siren sound which, otherwise, would be continuous.

The control sleeve I8 is provided with a suitable number of circumferentially extending and spaced slots 20 which are adapted to accommodate the previously referred to screws d employed for fastening the housing cap b to the main part a of the siren housing. These screws 01 and their cooperating slots 28 function to limit the extent to which the control sleeve I8 is permitted to move angularly in either direction.

Figs. 1, l and 5 disclose springs 2| which are employed for yieldably holding the control sleeve Iii in its position for uncovering the discharge ports 8 and for returning the control sleeve to that position after it has been moved to close the discharge ports. One end of each spring 2|, therefore, is connected to an ear 22 that projects radially, outwardly of the control sleeve 18 while the other end of each spring is anchored to the housing part a by a screw 23.

The mechanism employed for intermittently, angularly moving the control sleeve against the tension of the springs 2|, now will be described. It is to be understood that this drive mechanism is intended to move the control sleeve at a greatly reduced frequency relative to the speed of rotation of the impeller. It has been determined that an actuation frequency of 83 times per minutewith a rotor speed of 4500 R. P. M. produces Also, although the invention is not necessarily so limited, it is my intention that the control sleeve only be actuated during the periods when the rotor is operating at a speed equal to or in excess of approximately 3500 R. P. M.

The said drive mechanism includes a ring 24 that is suitably attached to and is positioned within the outer end portion of the control sleeve 18. This ring 24 has fastened to its opposite radial faces the plates 25. These plates are employed for supporting a pin 26 that is spaced radially inwardly of the inner face of the ring 25. Figs. 3 and 4 clearly illustrate this mechanism.

A speed reducing gear set 21 is carried by face plates 28 that are suitably fastened to the housing cap part b by means of the partition 29. The power output shaft 30 of this gear set projects inwardly of the partition 29 and is further supported by the bearing bracket 3| that is suitably fastened to the inner face of the siren housing cap b, as by means of the screws 32. This power output shaft 30, which will rotate at a speed of approximately 83 R. P. M., is provided with a laterally projecting pin 33 that is positioned to engage the pin 26 attached to the control sleeve l8. In other words, the pin 33 will engage the pin 26 at a frequency of approximately 83 times per minute and each time these two pins are engaged, the control sleeve I8 will be moved from its normal or idle position of Figs. 4 and 5 into its active position where it will close the circular series of air discharge ports 8 formed in the siren housing wall.

The power input shaft 34 of the speed reducing gear set 21 is journaled in a suitable anti-friction bearing 35 at its inner end and has a reduced outer end 36 that is supported and guided by a transverse brace 31 shown in Fig. 2 as being supported at its opposite ends by the bolts 38 which "fasten said 'ends'to .the' margin 'oflithe sirenimous- Zing cap. 22.

-Theiinner end-iof theepower input shafti3 itshas saifriction' clutch:plate;39 fastened-thereto. This :clutch plate is -a'daptedto be rot'ated only; That is to say, it does not partake of axial movement-to Z-effect engagementoridis'engagementof theiclutch. Theipower-input shaft-34 is axiallyzcounterbored atimiona'purpose that willbe'disclos'ed "ataa-Ilater point.

Returning -again to the hub: l i I of. the impeller, -it will -be-noted that its 'bore' has threaded. there- -in the end ii of: a-stub shaft that in'cludeshthe slightly:' 'enlarged,fsmooth surfaced :body: portion -42:- and :the slightly reduced opposite "end; portion s 43. iT-his stub shaft i l 42 l3,i therefore-.2 rovtates-w'ith the hub H2 of. the impeller.

sAi-doubleewingedrbracket A lis fastened to? the puteriend portion? or the smooth 'surfaced'dnter- -mediate parn- 42: of; the: stub shaft :bymeanstof a zmounting lring 45. Eachione 'zoff the iwings dli tol the-bracket 44 has pas'singtherethroughuthe mounting pins 4'! of the two centrifugail-lyactuated tweights 48. lThese weights are adapted toI be 'S-m0Ved"flOIII- thetposition illustrated in EigsI 3, 4 and 6' intoithepositionilillustratediin*Fig: 7- whenever thetspeediotthe stubzshaft 4 i-"r-t 2443=equals approximately 35flo'Bh-Pz M.

wThe'fcentrifugally actuated weights' 48x. are'rprm 4 videds'with'ipinsMirsee particularly Figsxfitzandtfl, which are: engaged in the".groovedperiphery ofa "shiftingicollar Sit 'Jadaptedi totslidel axially oft-the "smooth-isurfacedreportion" 42 of the stub' shaft. rrSIidable: movement'fof this shiftablez'collaraiifiilr -is yieldably resisted by means of the .spring l Athat surroundsfthe part ofthe stub shaft.

The shiftable collar 59 is provided with two rods 52 that are arranged" on diametrically opposite sides of the said stub shaft and project beyond the outer extremity of the reduced portion 43 of the stub shaft.

These rods have their outer-end portions anchored-to an axially shiftable clutch hub 53 provided with'a socket-5 latone end that zslidably receives the' reduced outer end portion-43 of the stub shaft. This reduced shaftxportion istipro- -vided-witha groove 55 that slidably receives the pin or screw 55 carried by the clutch hub 53. Consequently, every time the centrifugally actuated weights 43 are thrown outwardly, they move the shiftable collar 50 axially of the smooth intermediate portion 42 of the stub shaft and this movement of the collar 50, through the medium of the two rods 52, eifects axial shifting movement of the clutch hub 53 relative to the stub shaft portion 43.

The clutch hub 53 has threaded in its outer end the shank 51 of the shiitable clutch plate 58. This clutch plate 58 may be formed of any suitable friction material that is capable of driving the clutch plate 39 of the speed reducer gear set 21. It is to be understood that every time the centrifugally actuated weights 48 are thrown outwardly, by the speed of rotation of the stub shaft 41-42-43, the shiftable clutch plate 58 will be moved into driving engagement with the face of the gear train clutch plate 39.

To assure proper axial alignment of these two clutch plates 58 and 39, a centering pin 53 pro- J'ects axially of the clutch plate 58 and its shank 51 and is slidably received in the bore 40 of the power input shaft 34.

It will be appreciated from the above description of the mechanism for driving the control sleeve I 8 that this sleeve will be intermittently actuatdsto .closetthei. airtdischargeuportsiil: the

JSirBnluhousingTpQTt 11; at; slowifrequencysrelaltive toi the speedtoffrotation of the .aimpeller; andi'that the oon trol gsleeve- 1.8 vverily-will be actuated-ai men 5 .Zbhe': impellerspeedcequ'als" and 'exceeds approxim'at'elyli?500412. 29.M. Off'course, it willazbeaappreciatedl' that 'iftthei electriclmotor c'of .the'a'siren ish-not permittedtto I accelerate 1 to theaspeedlxat whi'ch -theacentritugally:actuated weights Mare lzthrowrr outwardly before. the :circuitfonthezsiren motor is brbkem thel siren can: be'operated w'thout having 'the controlasleeve 18' function: internfi ttently interrupttheaproduction or athe oonventional siremsound. e Eig 1. discloses-the tworcircuit wiresiilile-andlBZ iorsupplying-current. to-the electric sm'otor t the vsiren. Any suitable :iormitof circuit: makingnand I. breaking sw-itchi' 63*1may be conne'cteditinnseries cin either -one of these circuit wires" 6 I: oi liZ.

ll ln: a siren; the combination with. a housing haulng= a pluralityof spaced 5 discharge po'rts formed in a wall thereof v and -power:-Jd riventrotat'able' means forcirc'ulating air under pressure in a the housing and for expelling the air through 'said :dischargemorts-at rapidly recurring intervals to produce' the usual-"continuous sirenz sound bfta control memberassociated with: 'said' dis'charge po'rts and adapted to be moved into diiferent posil :'tions for alternatelynopening and closing -sa'id p ortato intermittently interrupts'aid'continuous "siren =sound, and drive means operated byazsaid rpower driven -'1'otatable meansfoi' moving*--said control member into said-"different pos'i-tions 'atla irequency that is substantially lower than' that bf therotatable:means.

2. "in a siren; the -combination -with a housing "-having- 1 a I plurality or spaced discharge ports formed=in= a wall thereof,- and' power dri'ven rotatable means for circulating-air under pressure in thehousing-ancl for expelling the airthrou'gh said discharge por-ts'--at rapidly recurring intervtrlg to tproduce the usualcontinuoussiren sound, inf a control -member associated'with said discharge ports-and adapted tobemoved into different positions for alternately" opening and closing said ports-to intermittently interrup said'continuous siren so'und, and" drive means "operatd -by' said power driven rotatable means for moving said control member into said different positions at a frequency that is substantially lower than that of the rotatable means, said drive means including a normally disengaged clutch assembly, and centrifugally actuated means rotated by said power driven rotatable means and operable to engage said clutch assembly only when said rotatable means is rotating in excess of a predetermined speed.

3. In a siren, the combination with a housing having an annular series of spaced discharge ports formed in a wall thereof, a power driven impeller in the housing for circulating air under pressure and expelling it through said discharge ports at rapidly recurring intervals to produce the usual continuous siren sound, of a control sleeve angularly movable in opposite directions in the housing radially inwardly of and having an annular series of discharge ports spaced to register with the housing discharge ports, the movements of the control sleeve in opposite directions effecting alternate aligning and disaligning of the two series of discharge ports for intermittently interrupting said continuous siren sound, and drive means operated by said impeller for moving the control sleeve at a frequency that is substantially lower than that of the impeller.

4. In a siren, the combination with a housing having an annular series of spaced discharge ports formed in a wall thereof, a power driven impeller in the housing for circulating air under pressure and expelling it through said discharge ports at rapidly recurring intervals to produce the usual continuous siren sound, of a control sleeve angularly movable in opposite directions in the housing radially inwardly of and having an annular series of discharge ports spaced to register with the housing discharge ports, the movements of the control sleeve in opposite directions effecting alternate aligning and disaligning of the two series of discharge ports for intermittently interrupting said continuous siren sound, and drive means operated by said impeller for moving the control sleeve at a frequency that is substantially lower than that of the impeller, said drive means including a normally disengaged clutch assembly, and centrifugally actuated means rotated by said impeller and operable to engage said clutch assembly only when said impeller is rotating in excess of a predetermined speed.

5. In a siren, the combination with a housing having a plurality of spaced discharge ports formed in a wall thereof, and power driven rotatable means for circulating air under pressure in the housing and for expelling the air through said discharge ports at rapidly recurring intervals to produce the usual continuous siren sound, of a control member associated with said discharge ports and adapted to be moved, into difierent positions for alternately opening and closing said ports to intermittently interrupt said continuous siren sound, and drive means operated by said power driven rotatable means for moving said control member into said different positions at a frequency that is substantially lower than that of the rotatable means, said drive means including a shiftable clutch member rotating with the power driven rotable means, centrifugally actuated weight means rotating with the rotatable means and operatively connected to the clutch member to shift the latter when the power driven rotatable means is rotating in excess of a predetermined speed, a speed reducing gear set having a driving clutch member engaged by the first mentioned clutch member, when it is shifted, to drive the gear set from the power driven rotatable means, and means at the output end of the gear set for moving the control member.

6. In a siren, the combination with a housing having an annular series of spaced discharge ports formed in a wall thereof, a power driven impeller in the housing for circulating air under pressure and expelling it through said discharge ports at rapidly recurring intervals to produce the usual continuous siren sound, of a control sleeve angularly movable in opposite directions in the housing radially inwardly of and having an annular series of discharge ports spaced to register with the housing discharge ports, the movements of the control sleeve in opposite directions efiecting alternate aligning and disaligning oi the two series of discharge ports for intermittently interrupting said continuous siren sound, and drive means operated by said impeller for moving the control sleeve at a frequency that is substantially lower than that of the impeller, said drive means including a shiftable clutch member rotatable with the impeller, centrifugally actuated weight means rotating with the impeller and operatively connected to the clutch member to shift the latter when the impeller is rotating in excess of a predetermined speed, a speed reducing gear set having a driving clutch member engaged by the first mentioned clutch member, when it is shifted, to drive the gear set from the impeller, and means .at the output end of the gear set for moving the control sleeve.

JOHN FLOYD FLETCHER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,520,225 Cosgrave et al. Dec. 23, 1924 1,941,324 Schirmer Dec. 26, 1933 1,985,954 Settegast Jan. 1, 1935 2,074,263 Harris, Jr., et a1. Mar. 16, 1937 

